This, unfortunately, could have been foreseen. Much is made of Jose Mourinho's inability to bring the best from young attackers under his tutelage. As has been well documented, two of the world's leading creative talents -- Liverpool's Mohamed Salah and Manchester City's Kevin de Bruyne -- have flourished elsewhere after Mourinho showed little faith in them.

Closer to home, it cannot be said that Marcus Rashford, despite a couple of brilliant outings last season, is consistently thriving. Martial must now watch as France, a national team in which he once had a starting spot, begin a World Cup where many view them as the favourites. At some level, that must be devastating for him.

Martial's career is at a crucial point. He is still young enough to reach extraordinary heights -- Salah and De Bruyne have already proved that. Yet at 22 he must be playing regularly and that does not look like a reasonable expectation under Mourinho. Even when United were flourishing at the beginning of last season, Martial found himself only an option from the bench, alternating superbly with Rashford. When he arrived at Old Trafford as the world's most expensive teenager in 2015, being restricted to brilliant cameos is probably not what he had in mind.

Anthony Martial has been at Manchester United since 2015. Getty

It is very clear that at United it is Mourinho's way or the highway, and it doesn't seem as though Martial has much option other than to leave. He finds himself behind Alexis Sanchez, who seems to have been signed to provide a more reliable source of goals -- even though the Chile forward, in almost 20 appearances for his new club, has thus far failed to be prolific.

Perhaps gallingly, he also finds himself behind Jesse Lingard, a fine player but whose talent does not match that of Martial. The Frenchman can also reflect that he has not been given the best chance of success. For much of his time at Old Trafford, he has been out on the left wing playing ahead of a full-back who rarely overlaps, meaning that he is often surrounded by three defenders with little support.

That scenario is no fun for him, not to mention his team's followers, and it is no wonder that he has apparently snapped. He should have no shortage of offers and it is striking to think that he would likely flourish under Jurgen Klopp, Mauricio Pochettino or Pep Guardiola. For that reason he should probably be sold abroad, where Barcelona or Real Madrid -- as a long-term replacement for Karim Benzema -- would be plausible and excellent destinations.

Should he leave, it would be a tremendous loss. This is a man who decided a game against Liverpool on his debut with a solo goal of rare brilliance, and who decided an FA Cup semifinal with a last-minute winner of even rarer composure. He seemed to have everything it took to be a United great. He could still go down as one of the finest forwards of the modern era -- it sadly looks as though it will not be at Old Trafford.